Device for reinforcing a hollow element of a motor vehicle

ABSTRACT

The invention relates to a device for reinforcing a hollow element ( 16 ) of a motor vehicle, especially a column of the body. The inventive device consists of at least one elongate, dimensionally stable plastic support frame ( 10 ) insertable into the hollow element ( 16 ) which is provided with free supporting surfaces ( 18 ) that can be engaged gaged with the inner wall ( 32 ) of the hollow element ( 16 ).

The invention relates to a device for reinforcing a hollow element of avehicle, in particular a vehicle-body pillar.

For this purpose, in automobile building, reinforcing parts are known asa composite body comprising a geometrically simple load-bearingstructure and a foamable material. The load-bearing structure servesprimarily to retain and place the foamable material in a hollow partwithout any special contour adaptation. Next, the hollow part is filledwith foam to its full volume, and the expanded foam material providesthe connection to the wall and thus the absorption of force anddistribution of load. The reinforcement effect is thus definitivelybased on the material properties of the foam. It has provendisadvantageous in this respect that the foaming process requires achemical reaction that must be adapted to the production process of thevehicle, particularly in terms of the incident temperatures. Thereinforcement function thus depends on accurate and constant adherenceto the process parameters. Another disadvantage is that the structuralparts can no longer be disconnected from one another easily, makingrecycling more difficult. In addition, completely filling the space withfoam brings about a more or less homogeneous reinforcement effect,without the ability to take three-dimensional varying designrequirements into account.

With this as the background, it is the object of the invention toovercome the aforementioned disadvantages and to create a hollow elementreinforcement which is simple to produce and simple to use, can bedesigned variably to suit specific stresses, makes weight reductionpossible, and presents no particular problems of disposal.

For attaining this object, the combination of characteristics recited inclaim 1 is proposed. Advantageous features and refinements of theinvention will become apparent from the dependent claims.

The invention is based on the concept of creating a reinforcing body asa lightweight component that is free of load-bearing foam parts. Henceaccording to the invention, an elongated, dimensionally stablesupporting skeleton of plastic is proposed which is insertable into thehollow element and has free support faces that can be brought intoengagement with the inner wall of the hollow element. With extensiveweight reduction, the plastic skeleton structure makes geometricallycomplex shaping and a three-dimensionally adapted reinforcement behaviorfeasible; the outer support faces allow a load to be absorbed directly.The supporting skeleton has a defined function, because of itspredetermined structure. Its assembly can be incorporated, withoutparticular effort or expense, into the existing production sequence ofthe vehicle, and simple disconnection into pure types of material ispossible for the sake of disposal.

Advantageously, the supporting skeleton has an envelope contourcorresponding to the inside shape of the hollow element.

An optimal design is made possible because the supporting skeleton isembodied as an integral molded part, preferably as an injection-moldedpart. In terms of the dimensional stability in production and use of thevehicle, it is advantageous if the supporting skeleton comprises aheat-resistant plastic, preferably polyphenyl sulfide in the form ofhigh-performance plastic, or polyamide.

A structurally advantageous design provides that the supporting skeletonhas, distributed over its length, a plurality of bracing ribs extendingtransversely to its longitudinal direction. The intent is to assure thatthe bracing ribs each span an internal cross section, preferably overthe full area thereof, of the hollow part, in order to achieve optimalbracing. A further advantage in this respect is obtained because thebracing ribs are kept spaced apart from one another via longitudinalstruts of the supporting skeleton. In this respect it is favorable ifthe supporting skeleton has at least one and preferably two longitudinalstruts that are continuous in its longitudinal direction andtransversely penetrate the bracing ribs.

To optimize the introduction of force, it is advantageous if theperipheral edges of the bracing ribs and optionally the longitudinalstruts are adapted, as support faces, to the contour of the inner wallof the hollow element.

A further advantageous feature of the invention provides that thestructural strength of the supporting skeleton is adapted or modeled inaccordance with the specification of a three-dimensionally variableoperative stiffness and/or crash stress. This can be achieved, inaccordance with the desired deformation behavior, by providing that thewall thickness, the mutual spacing, and/or the orientation of thebracing ribs and/or longitudinal struts varies over the supportingskeleton.

For structurally optimized weight reduction, it is advantageous if thesupporting skeleton has a plurality of hollow chambers, which areseparated from one another in the longitudinal direction of thesupporting skeleton by the bracing ribs and are open in a transversedirection.

Advantageously, the bracing ribs have shoulder portions protruding tothe outside laterally past the longitudinal struts.

A further advantageous version provides that the supporting skeleton hasrecesses for functional parts, such as belt rollers, that are integratedwith the hollow element.

For direct force introduction and bracing, the supporting skeleton canrest by positive engagement at its support faces against the inner wallof the hollow element. To further improve the operative stiffness, it isfavorable if the supporting skeleton can be brought into nonpositiveand/or material engagement with the inner wall of the hollow element viaconnecting means that are preferably applied in layers to its supportfaces, to which end an adhesive or an adhesive foam that is activatableby the action of heat is advantageous. In addition or as an alternative,the supporting skeleton can be fixed in the hollow element via separatemechanical connecting means.

An additional function is attained by providing that foamable parts aredisposed on the supporting skeleton for sealing off or partitioning offa cross section of the hollow element.

With relatively long hollow parts, a plurality of supporting skeletonscan be disposed in line with one another, as shown in FIG. 8, to avoidtolerance problems. Optionally, the supporting skeletons can be coupledto one another at the ends, preferably via plug-in or articulatedconnections 38.

A further aspect of the invention relates to a structural part of avehicle, comprising a hollow element and at least one supportingskeleton, inserted into it, in accordance with the invention.

The invention is described in further detail below in terms of anexemplary embodiment shown schematically in the drawings. Shown are

FIG. 1, a perspective view of a supporting skeleton for insertion into aB pillar of a motor vehicle;

FIG. 2, a side view of the supporting skeleton of FIG. 1;

FIG. 3, a perspective view of the supporting skeleton, inserted withpositive engagement into the B pillar;

FIG. 4, a vertical section through the inner wall, shown cut away, ofthe B pillar and the supporting skeleton inserted into it;

FIGS. 5-7, a section along the correspondingly numbered section lines inFIG. 4; and

FIG. 8, a perspective view of two supporting skeletons coupled together.

The elongated supporting skeleton 10 shown in FIG. 1, as a plasticintegral molded part, comprises two longitudinal struts 12, extendingparallel to one another in the longitudinal direction of the skeleton,and a plurality of bracing ribs 14 extending transversely to thelongitudinal struts and laterally spaced apart from one another. Theenveloping contour spanned by the supporting skeleton 10 corresponds tothe internal shape of the B pillar 16 or in general a hollow part of avehicle, the vehicle not being shown separately. In the inserted state,the supporting skeleton 10 thus makes a structural reinforcementpossible, and in particular a bracing that is adapted to the loadrequirements.

For this purpose, the bracing ribs 14 and the longitudinal struts 12,with their edges, form outward-pointing free support faces or supportedges 18, which can be brought into pointwise or linear engagement withthe hollow part on the inside. To meet spatially varying demands forstrength of the supporting skeleton 10, the wall thickness and themutual spacing of at least the bracing ribs 14 are adapted accordingly,or in other words are embodied differently at intervals over thesupporting skeleton. The structural design is in accordance withcomputer or experimental analysis of the operative and crash stressfeatures of the vehicle.

The supporting skeleton 10 of lightweight construction has many hollowchambers 20, which are disposed in lines in the longitudinal directionof the skeleton and are open transversely to it, and which are separatedfrom one another in trestle fashion by the bracing ribs 14 and thelongitudinal struts 12. To be able to span even complex hollow chambercross sections over the full area, the bracing ribs 14 have centralportions 22 that extend between respective longitudinal struts 12 andalso have shoulder portions 24 that project laterally past thelongitudinal struts 12. For receiving functional parts integrated withthe hollow element, such as a belt roller, not shown, the supportingskeleton 10 is provided with suitable recesses 26 (FIG. 2).

As best seen from FIG. 3, the supporting skeleton 10 can be insertedinto the sheet-metal part 28, which is of complementary shape and opentoward the outside, of the B pillar 16. Optionally, mechanical fasteningmeans, not shown, can be provided for additional fixation. In the courseof further vehicle assembly, the B pillar is closed with an outersheet-metal part 30, thereby enclosing the supporting skeleton 10. Thesheet-metal parts 28, 30 form the geometrically complex shaped innerwall 32 of the B pillar 16 (FIG. 4).

FIGS. 5-7 show cross sections at various levels through the structuralpart 34 formed of the sheet-metal parts 28, 30 and the supportingskeleton 10 disposed in them. The bracing ribs 14, with their supportingedges 18, make bracing all the way around possible over the respectivecross sectional contour of the inner wall 32, while the supporting edges18 of the longitudinal struts 12 follow the longitudinal contour of thehollow element 16. In this way, even creasing and compression stressesthat occur at points can be absorbed and dissipated over greatersupporting widths along the supporting skeleton 10.

In principle, it is possible for the supporting skeleton 10 to be joinedby nonpositive and/or material engagement to the inner wall 32 viamechanical or adhesive connecting means that are expediently applied, inparticular at some places to the supporting edges 18 of the skeleton.For that purpose, as shown in FIG. 5, a material 36 that is a separatemechanical connecting means or is capable of foaming under the action ofheat can be provided, such as a polyethylene-based foam. As a result,any tolerances and thermal expansions that occur can be compensated for,and a secure, rattle-free connection can be achieved. The foaming isadvantageously done during subsequent heating of the vehicle body, forinstance in the cataphoretic coating process. It is understood that itmust be assured that the supporting skeleton 10 comprise a suitabletemperature-resistant material to withstand the incident temperatures ofapproximately 150 to 190° C. of that process.

Supporting skeletons of the type described above can preferably be usedin vehicle pillars, but can also be used in frame parts, roof struts,motor supports, or chassis parts of motor vehicles without significanteffort or expense of assembly, for achieving highly effective,low-weight reinforcement. The structural design can suit locallyvariable requirements for strength, which proves advantageousparticularly for hollow elements of the kind that for the sake ofreducing weight are made of sheet-metal parts of varying wall thickness.

1. A device for reinforcing a hollow element of a vehicle, comprising atleast one elongated, dimensionally stable supporting skeleton ofplastic, which is insertable into the hollow element and has freesupport faces that can be brought into engagement with the inner wall ofthe hollow element, wherein the supporting skeleton is embodied as anintegral molded part and has, distributed over its length, a pluralityof bracing ribs extending transversely to its longitudinal direction,which are kept spaced apart from one another via at least onelongitudinal strut in the supporting skeleton, whereby the longitudinalstrut(s) run(s) in the longitudinal direction of the hollow element andwhereby the bracing ribs each span an internal cross section over thefull area of the hollow element and whereby the peripheral edges of thebracing ribs are adapted as support faces to the contour of the innerwall of the hollow element.
 2. The device of claim 1, wherein thesupporting skeleton has an envelope contour corresponding to the insideshape of the hollow element.
 3. The device of claim 1, wherein thesupporting skeleton is embodied as an injection-molded part.
 4. Thedevice of claim 1, wherein the supporting skeleton comprises aheat-resistant plastic.
 5. The device of claim 1, wherein thelongitudinal strut(s) is (are) continuous in the longitudinal directionand transversely penetrate the bracing ribs.
 6. The device of claim 1,wherein the peripheral edges of the longitudinal struts are adapted, assupport faces, to the contour of the inner wall of the hollow element.7. The device of claim 1, wherein the structural strength of thesupporting skeleton is adapted in accordance with the specification of athree-dimensionally variable operative stiffness or crash stress or bothoperative stiffness and crash stress.
 8. The device of claim 1, whereinone or more of the wall thickness, the mutual spacing, or theorientation of either the bracing ribs or the longitudinal struts orboth bracing ribs and longitudinal struts varies over the supportingskeleton (10).
 9. The device of claim 1, wherein the supporting skeletonhas a plurality of hollow through chambers, which are separated from oneanother in the longitudinal direction of the supporting skeleton by thebracing ribs and are open in a transverse direction.
 10. The device ofclaim 1, wherein the bracing ribs have shoulder portions protruding tothe outside laterally past the longitudinal struts.
 11. The device ofclaim 1, wherein the supporting skeleton has recesses for functionalparts that are integrated with the hollow element.
 12. The device ofclaim 1, wherein the supporting skeleton rests by positive engagement atits support faces against the inner wall of the hollow element.
 13. Thedevice of claim 1, wherein the supporting skeleton can be brought intononpositive or material engagement with the inner wall of the hollowelement via connecting means optionally applied in layers to supportfaces of the supporting skeleton.
 14. The device of claim 13, wherein anadhesive or an adhesive foam is provided as the connecting means. 15.The device of claim 14, wherein the adhesive foam is activatable by theaction of heat.
 16. The device of claim 1, wherein the supportingskeleton is fixable in the hollow element (16) via separate mechanicalconnecting means.
 17. The device of claim 1, wherein foamable parts aredisposed on the supporting skeleton for sealing off or partitioning offa cross section of the hollow element.
 18. The device of claim 1,wherein a plurality of supporting skeletons are distributed over thelength of the hollow element.
 19. The device of claim 18, wherein thesupporting skeletons are coupled to one another at the ends.
 20. Thedevice of claim 1, wherein the hollow element is a structural part of avehicle.
 21. The device of claim 11, wherein the functional part is abelt roller.
 22. The device of claim 4, wherein the heat-resistantplastic is a polyphenyl sulfide.
 23. The device of claim 5, wherein thesupporting skeleton has two longitudinal struts.
 24. The device of claim19, wherein the supporting skeletons are coupled to one another at theends via plug-in or articulated connections.
 25. The device of claim 20,wherein the structural part is a vehicle body pillar.